Trachte: Adrenergic Agonists Flashcards
What is NE synthesized from?
Tyrosine
What acts on B1 receptors?
Isoproterenol> Epi = NE
Where are B1 receptors located?
Heart
JG apparatus
Adipose tissue
What does stimulation of B1 receptors lead to?
Galpha>
increase cAMP>
adrenergic cardiac effects, renin release
What acts on A1 recetpors?
Epi> NE» Iso
Where are A1 receptors located and what do they do?
blood vessels>
Smooth muscle contraction
What g protein are A1 receptors coupled to?
Galpha a>
phospholipiase C>
inositol triphosphates>
increase intracellular CA
What acts on B2 receptors?
iso> epi» NE
What does stimulation of B2 receptors do?
relax smooth muscle
metabolic effects
Where are B2 receptors located?
Blood vessels (smooth muscle)
What G protein are B2 receptors coupled with?
G alpha s>
increase c AMP
What acts on A2 receptors?
Epi> NE» Iso
What does stimulation of A2 receptors do?
Inhibits NE release
Where are A2 receptors locate?
Prejunctional nerve terminal, platelets, gut, medulla oblongata
How do A2 receptors decrease cAMP?
G aplha i>
decrease cAMP or activate Na/H antiporter
What do dopaminergic receptors interact with? What does this do?
DA
dilate renal and mesenteric vasculature
What is Dobutamine?
B1 agonist
What does Dobutamine do to blood pressure and what will block that effect?
INCREASE BP
Blocked by propranolol
What is dobutamine used for?
CHF
AMI w/ heart failure
What is phenylphrine?
alpha 1 agonists
What is phenylphrine used for?
reverse hypotension
paroxysmal atrial tachycardia
What is used to treat orthostatic hypotension?
Midodrine
What does phenylphrine do to blood pressure? What blocks it?
Increases blood pressure
Blocked by Terazosin
What receptor does Metaprotenrenol, Terbutaline, Albuterol and Salmeterol act on?
B2 selective agonist
What is albuterol used for?
Bronchodilation
Asthma- B2 agonists
What drugs are used to delay labor?
ritodrineterbutaline
What are side effects of B1 stimulatoin
Tachycardia, palpitations
What are side effects of B2 stimulation?
tremor and headache
What is the major cardiovascular effect to iv injection of a B2 selective agonist?
Vasodilation
What does albuterol do to blood pressure? What would block that action?
Decreases blood pressure
Propranolol
Whatare Clonidine, methyldopa, guanabenz and tizanidine?
A2 agonists
What is an antihypertensive that’s safe to use in pregnancy?
Methyldopa
What drugs decrease sympathetic activity without interfering with reflexes?
Guanabenz, Guanfacine
What is clonidine used for?
ADD
What are side effects of A2 receptor agonists?
Depression
Sexual dysfunction
Dry mouth
bradycardia
What do alpha 2 agonists do to blood pressure?
Increase blood pressure
What happens when Epi stimulates A1 vs B2?
A1- vasoconstricts
B2- vasodilate
What does Epi do in the cardiovascular system?
INCREASES HR and force but reflexes to elevation in BP can suppress HR (vagal stimulation)
What does Epi do to blood pressure?
Increases blood pressure
What happens when EPI is blocked by terazosin?
Brings blood pressure back to normal
What happens if you give Epi and terazosin?
Decrease BP
What happens when you give epi after giving terazosin and propranolol?
BP stays the same
What does NE do?
A1- vasoconstriction
B1- increase heart rate and force
(reflex reduction in HR–mediated by vagus nerve)
What does NE do to bp?
Increases BP
What happens if you administer NE after giving terozosin?
Smaller increase in BP
What happens if you give NE after giving terazosin and propranolol?
Bp stays the same
What does isoproternol do?
B2- vasodilation
B1- tachycardia
What is isoproterenol used for?
B1 cardiac stimulation
Stimulation of what receptor increases CO?
B1
Stimulation of what receptor increases TPR?
B1, A1
Stimulation of what receptor decreases HR?
Muscarinic
Stimulation of what receptor decreases TPR?
Muscarinic and B2
What does affect does dopamine have on B1, dopaminergic, A1 and the neural system?
B1- positive ionotrope
Dopaminergic- vasodilator of renal and mesenteric vasculature
A1- vasoconstrictor at high doses
Neural- releases NE from nerves
What is DA used for?
Maintains renal perfusion
Hypotension
Increased BP and CO
What do indirectly acting agents (like NE and Amphetamine) do?
Release NE from nerves by reversing the catecholamine axoplamic uptake pump>
increases BP